Nicotinic acetylcholine receptors (AChRs) are ligand-gated ion channels in the central nervous system that mediate addiction to nicotine in tobacco products. Tobacco use is responsible for a catastrophic number of deaths (>400,000) per year in the U.S. alone and a health care-related expenditure of approximately $50 billion. It is likely that repetitive activation of AChRs by nicotine first leads to fundamental changes in the structure, functional properties and cell surface density of AChRs. These changes, in turn, drive long-term adaptive changes in the properties of functional neuronal networks (e.g. mesocorticolimbic) that mediate addictive behaviors and thus lead to tobacco addiction. Our long-term goal is to understand the biological mechanisms that regulate the biogenesis, structure, functions and cellular localization of AChRs. Over the last few years, our laboratory has identified several novel cytosolic proteins that interact with the alpha4beta2 AChR, a subtype that is widely expressed in the central nervous system and implicated in mediating addiction to nicotine. The objectives of this RO1 proposal are to test specific hypotheses about alpha4beta2 AChR determinants and their complementary interactors that regulate the biogenesis of the alpha4beta2 AChRs with respect to their 1) stoichiometry;2) axonal/dendritic targeting;3) clustering and 4) cell surface density. These hypotheses are based on extensive new preliminary data, as well as published results of the initial characterization of the interaction of cytosolic proteins that interact with alpha4beta2 AChR. The results obtained from these studies will provide a better understanding of the biological mechanisms that regulate plasticity in alpha4beta2 AChR structure, transport, distribution and surface expression. Nicotinic acetylcholine receptors (AChRs) are ion channels in brain cells that mediate addiction to nicotine in tobacco products. Tobacco use causes a catastrophic number of deaths (>400,000) per year in the U.S. alone and a health care-related expenditure of approximately $50 billion. The results obtained from the proposed studies will provide a better understanding of biological mechanisms that lead to tobacco addiction and whose disruption may be particularly relevant in neurological diseases such as Alzheimer's disease and schizoaffective disorders.